JPH07164251A - Manufacture of shaft for gas bearing - Google Patents

Abstract

PURPOSE:To provide a method by which a shaft for a gas bearing having a herringbone type dynamic pressure generation groove and another groove for air sump adjacent to the former groove can be produced at a low cost. CONSTITUTION:In the manufacturing method of a shaft 1 for gas bearing having a herringbone type dynamic pressure generation groove 2 and another groove 3 for an air sump adjacent to the former groove, the herringbone type dynamic pressure generation groove 2 is formed by rolling after forming a groove 3 for the air sump on a work 1'. The groove 3 is formed by grinding by a lathe, cylindrical grinding or centerless grinding and kept deeper than the groove 2. As only the herringbone type dynamic generation groove 2 is required to be rolled, a force applied to a rolling metal mold device becomes smaller and a device can be miniaturized and its cost can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision high-speed motor for OA equipment such as a high-speed polygon scanner motor for an optical scanning device mounted on a laser beam printer, a digital copying machine, a spindle for high-speed rotation, etc. The present invention relates to a gas bearing for a rotating body that requires precise and high-speed rotation, and particularly to a method for manufacturing a shaft for a dynamic pressure gas bearing.

[0002]

2. Description of the Related Art FIG. 3 shows a shaft used for a dynamic pressure gas bearing. As shown in the figure, on the surface of the shaft 1, there are a number of thin herringbone type dynamic pressure generating grooves 2 arranged in a V shape, and a width formed by circulating the grooves 2 around the outer circumference of the shaft 1. And a wide air trap groove 3 are formed. The herringbone type dynamic pressure generating groove 2 acts to generate a high-speed airflow by rotating the shaft 1 at a high speed, and thereby to lift the shaft 1 from the bearing. The air trap groove 3 is the dynamic pressure generating groove 2
Is the place to supply the air drawn in.

As a means for processing the dynamic pressure generating groove 2 and the air trap groove 3 of the shaft 1, photolithographic etching has been widely used in the past, but recently,
Manufacturing by rolling has been adopted, and significant cost reductions have come to be achieved.

FIG. 4 is a plan view of the rolling die forming the shaft 1 of FIG. The die 4 has a first convex portion 5 corresponding to the air trap groove 3 of the shaft 1 and a herringbone type dynamic pressure generating groove 2 that obliquely projects vertically from the first convex portion 5 like a fish bone. A large number of corresponding second convex portions 6 are formed. A round bar-shaped material 1'shown in FIG.
By rolling between them, the shaft 1 shown in FIG. 3 is formed.

However, according to the conventional rolling method,
Since the area of the air trap groove 3 is several times larger than the area of the herringbone type dynamic pressure generating groove 2, it is very large in order to bite the first convex portion 5 of the rolling die 4 into the work. Processing pressure is required. As a result, the rolling die device must be structurally robust, and it will be a large-scale one that uses hydraulic pressure, etc., resulting in high equipment costs and ultimately an expensive gas bearing itself. .

The present invention is intended to solve the above problems, and an object thereof is to provide a method for manufacturing a gas bearing shaft at low cost.

[0007]

To achieve the above object, the present invention provides a method for manufacturing a gas bearing shaft having a herringbone type dynamic pressure generating groove and an air reservoir groove adjacent to the groove. After forming the groove for air accumulation on the shaft,
The herringbone type dynamic pressure generating groove is formed by rolling.

Further, the depth of the air reservoir groove may be deeper than the depth of the herringbone type dynamic pressure generating groove, the air reservoir groove may be formed by cutting, or the air reservoir may be formed. It is desirable that the groove be formed by cylindrical grinding or centerless processing.

[0009]

Operation: Before forming the herringbone type dynamic pressure generating groove on the shaft by rolling, the air trap groove is formed by cutting or the like.
The rolling die only needs to form the herringbone type dynamic pressure generating groove, and the force required for rolling can be significantly reduced. If the depth of the air trap groove is made deeper than the depth of the herringbone type dynamic pressure generating groove, it is possible to guarantee the reduction of the force applied to the rolling die. Therefore, the rolling die apparatus can be downsized, and the shaft can be manufactured at low cost.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 (a) to 1 (c) are views showing the steps from the work 1'to the completion of the shaft 1. FIG. (a) shows a work 1'in a round bar state before being processed into a shaft. (b) shows a state 1 ″ in which the air trap groove 3 is formed in the work 1 ′ shown in (a). The air trap groove 3 has the same depth as the expected depth of the herringbone type dynamic pressure generating groove 2. Grinded.

Thereafter, when the herringbone type dynamic pressure generating groove 2 is formed by the rolling die 4 shown in FIG. 4, the shaft 1 as shown in FIG. 1 (c) is formed. According to this method, since it is not necessary to form the air trap groove 3, the force required for processing is only the force that the second convex portion 6 of the die 4 bites into the work 1 ″. The size of the rolling die 4 is much smaller than that of the conventional method in which the die 4 and the work 1 ″ are easily positioned by fitting the first convex portion 5 of the rolling die 4 into the air pool groove 3. it can. Figure 1 (d) is
It is a DD sectional view of (c).

Since the herdbone type dynamic pressure generating groove 2 serves only as an air supply source when the herringbone type dynamic pressure generating groove 2 draws in air, the herringbone type dynamic pressure generating groove 2 has a function. In comparison, the depth of the groove has a wide allowable limit, which is out of order. Therefore, the groove 3 for air trapping can be easily formed by grinding with a lathe, cylindrical grinding, or centerless processing using a grindstone formed into a predetermined shape. The most convenient one can be selected.

FIG. 2 is a diagram showing another embodiment of the present invention. As described above, the portion of the air trap groove 3 does not require accuracy. However, if the depth is smaller than the planned depth of the herringbone type dynamic pressure generating groove 2, the first of the die 4 is
The convex portion 5 hits the bottom of the air trap groove 3, and the force applied to the die becomes large. In order to reliably prevent this, in this embodiment, the depth d2 of the air trap groove 3 is made deeper than the depth d1 of the herringbone type dynamic pressure generating groove 2,
I'm running away.

With this structure, when the herringbone type dynamic pressure generating groove 2 is formed, the force applied to the rolling die can be limited to the force that surely bites into the groove 2, and the shaft can be made with a small force. 1 is guaranteed to be formed.

[0015]

As described above, according to the present invention,
Since the force required for rolling can be reduced, the rolling die device
Compared to conventional products, it can be made smaller and simpler, and the manufacturing cost of the shaft can be greatly reduced. Further, by making the groove for air accumulation deep, it is possible to ensure that the force applied to the rolling die is reduced.

[Brief description of drawings]

1A to 1C are views showing a process of manufacturing a shaft from a work, and FIG. 1D is a sectional view taken along line D-D of FIG. 1C.

FIG. 2 is a cross-sectional view corresponding to FIG. 1 (d) in another embodiment of the present invention.

FIG. 3 is a front view of a gas bearing shaft.

FIG. 4 is a plan view of a rolling die for manufacturing a shaft.

FIG. 5 is a front view of a work as a shaft material.

[Explanation of symbols]

 1 axis 2 herringbone type dynamic pressure generating groove 3 air trap groove 4 rolling die

Front page continuation (72) Hideo Sato Inventor Hideo Sato 3-1, Shinmei, Nakameisei, Shibata-cho, Shibata-gun, Miyagi Prefecture Tohoku Ricoh Co., Ltd. 1 Inside Tohoku Ricoh Co., Ltd.

Claims (4)

[Claims] 1. A method of manufacturing a gas bearing shaft having a herringbone type dynamic pressure generating groove and an air reservoir groove adjacent to the groove, wherein the herringbone is formed after the air reservoir groove is formed on the shaft. A method for manufacturing a gas bearing shaft, comprising forming a die dynamic pressure generating groove by rolling. 2. The method for manufacturing a gas bearing shaft according to claim 1, wherein the depth of the air reservoir groove is deeper than the depth of the herringbone type dynamic pressure generating groove. 3. The method for manufacturing a gas bearing shaft according to claim 1, wherein the air reservoir groove is formed by cutting. 4. The method for manufacturing a gas bearing shaft according to claim 1, wherein the air reservoir groove is formed by cylindrical grinding or centerless processing.